We present an accurate way to detect spin dynamics of a nutating molecular nanomagnet by inserting it in a tunnel Josephson junction and studying the current voltage (I-V) characteristic. The spin nutation of the molecular nanomagnet is generated by applying two circularly polarized magnetic fields. We demonstrate that modulation of the Josephson current by the nutation of the molecular nanomagnet's spin appears as a stepwise structure like Shapiro steps in the I-V characteristic of the junction. Width and heights of these Shapiro-like steps are determined by two parameters of the spin nutation, frequency and amplitude of the nutation, which are simply tuned by the applied magnetic fields.

Introduction: Reactive arthritis (ReA) is a joint inflammation that follows an infection at a distant site, often in the gastrointestinal or urogenital tract. Since the emergence of COVID-19 in January 2020, several case reports have suggested a relation between reactive arthritis and severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), due to the novelty of the disease, most findings were reported in the form of case reports or case series, and a comprehensive overview is still lacking. Methods: We searched PubMed/Medline and Embase to identify studies addressing the association between ReA and COVID-19. The following terms were used: [“Reactive Arthritis” OR “Post-Infectious Arthritis” OR “Post Infectious Arthritis”] AND [“COVID-19” OR “SARS-CoV-2” OR “2019-nCoV”]. Results: A total number of 35 reports published up to February 16th, 2022, were included in this study. A wide range of ages was affected (mean 41.0, min 4 max 78), with a higher prevalence of males (61.0%) from 16 countries. The number and location of the affected joints were different in included patients, with a higher prevalence of polyarthritis in 41.5% of all cases. Cutaneous manifestations and visual impairments were found as the most common associated symptoms. Most patients (95.1%) recovered, with a mean recovery time of 24 days. Moreover, arthritis induced by COVID-19 seems to relieve faster than ReA, followed by other infections. Conclusion: ReA can be a possible sequel of COVID-19 infection. Since musculoskeletal pain is a frequent symptom of COVID-19, ReA with rapid onset can easily be misdiagnosed. Therefore, clinicians should consider ReA a vital differential diagnosis in patients with post-COVID-19 joint swelling. Additional studies are required for further analysis and to corroborate these findings.

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